ixpand flash drive 2.0 prepare to sync stage hang and no progress

i’m using ixpand flash drive on my iPhone 6 and during stage of prepare to sync, it seems doesn’t progress and I tried wait for few hours but not sure if it is progressing. Anyone know what is the problem?

Mine is set to “automatically sync” my photos when the app is opened. However, it rarely does. I just do a manual sync and it then flies through.